The correct answer is Microsoft Defender for Office 365.

Microsoft Defender for Office 365 is specifically built to detect and stop sophisticated email based attacks such as phishing, spear phishing, and credential harvesting. It includes anti phishing policies, impersonation detection, Safe Links, Safe Attachments, and automated investigation and response capabilities that go beyond basic spam and malware filtering.

Microsoft Defender for Identity focuses on identity based threats in on premises and hybrid environments and it monitors lateral movement and suspicious authentications rather than providing email anti phishing protections.

Microsoft Purview Data Loss Prevention helps prevent accidental or intentional leakage of sensitive information by applying policies to content and data flows and it does not specialize in detecting phishing or credential theft campaigns.

Exchange Online Protection provides baseline spam and malware filtering for email but it is not designed to provide the advanced anti phishing, link rewriting, and attachment sandboxing features that Defender for Office 365 provides.

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